Na +-K + pump - in fact, Na +-K + ATP enzyme, exists in animals and plants cytoplasmic membrane, it has the size of the two subunits, the catalytic subunit of ATP hydrolysis, the small subunit is a glycoprotein. Na + -K + ATP enzyme through phosphorylation and phosphorylation of the process to conformational changes occur, leading to Na +, K + affinity change. Large subunit of Na + in the pro-state binding Na +, the trigger hydrolysis of ATP. Each of ATP hydrolysis to release the energy of a transfer to the three extracellular Na +, and two K + uptake into the cell, resulting in transmembrane gradient and potential difference, which is particularly important in nerve impulse conduction, Na +-K + pump caused by membrane potential difference of the nerve membrane voltage about 80%. If the purified Na +-K + pump assembly in the red cell membrane vesicles (blood film), the membrane on both sides of artificially increasing the Na +, K + gradient to a certain extent, When the gradient is greater than the energy held by the chemical energy of ATP hydrolysis when, Na +, K + concentration difference will reverse the flow Shun Na +-K + pump, while synthesis of ATP.
A sodium-potassium pump characteristics was his transfer of ions from the cycle of phosphorylation-dependent process, ATP a phosphate group transferred to a sodium-potassium pump at Asp residues, resulting in conformational changes. To the adoption of self-phosphorylation of the ion pump ion transporter called P-type, which are similar to calcium pump and proton pump. They formed a similar function and structure of a protein family.
Na +-K + pump function is: ① to maintain the permeability of cells to maintain cell volume; ② maintain a low Na + high K + within the cell environment, the maintenance of cell resting potential.
Ubundu glycoside (ouabain), digoxin (digoxin) and other cardiac myocytes can inhibit Na +-K + pump activity; thereby reducing the efficiency of sodium-calcium exchanger, so that increased calcium influx to enhance myocardial contractility, which has a strong heart role.